Thanks for the replies.
I have tried both:
{
"Backup": "1",
"Restore": "1",
"DateTime": "2016-09-28",
"Mirror": "2"
}
And
{
"Backup": "2",
"Restore": "1",
"DateTime": "2016-09-28 08:44:39"
}
I am still sure it has something to do with the date. If I remove the date time from the json it sends it up. The cell that is receiving the DateTime is a date on power bi side.